Thermostat system with software-repurposable wiring terminals adaptable for hvac systems of different ranges of complexity

ABSTRACT

An auxiliary hardware box is described that can be installed at or near the HVAC system. The auxiliary box includes a large number of wiring terminals, for example 16 or more, for connecting to a relatively large number of HVAC control wires. The auxiliary box can include a “train map” type graphic display that is visible to the installer and provides a graphical indication as to which relays or switches are currently open and which are currently closed. A small sleek visually pleasing thermostat is also described that can be connected either directly to an HVAC system or to the auxiliary box, and can automatically detect an purpose the connected wires according to which it is connected to.

This patent specification relates to systems, methods, and relatedcomputer program products for the monitoring and control ofenergy-consuming systems or other resource-consuming systems. Moreparticularly, this patent specification relates to a thermostat forconnection either directly to an HVAC system or to an intermediateauxiliary HVAC control unit.

BACKGROUND

When connecting to a thermostat to some types of modern residential HVACsystems there are sometimes quite a few wires used. In some cases therecan be as many as 16 wires. In designing a sleek thermostat that isvisually pleasing when wall mounted in a home, it is desirable that thethermostat is not overly large. Thus, there exists a design problem asto how to connect a large number of HVAC control wires to a relativelysmall thermostat.

Additionally, in some cases the circuitry required to generate sometypes of control signals can use a relatively large amount of space onthe thermostat. For example, in some systems where a “V” wire is usedfor variable control of fan speed, a relatively large amount ofcircuitry may be used within the thermostat to generate the signal.

Furthermore, in some cases when a common wire is not present, certaintypes of thermostat relays and/or switches make power stealingimpractical. In some cases adding a common wire between the HVAC systemand the thermostat is a costly endeavor.

It is to be appreciated that although exemplary embodiments arepresented herein for the particular context of HVAC system control,there are a wide variety of other resource usage contexts for which theembodiments are readily applicable including, but not limited to, waterusage, air usage, the usage of other natural resources, and the usage ofother (i.e., non-HVAC-related) forms of energy, as would be apparent tothe skilled artisan in view of the present disclosure. Therefore, suchapplication of the embodiments in such other resource usage contexts isnot outside the scope of the present teachings.

SUMMARY

According to one or more embodiments, a thermostat adapted for eitherdirect connection to an HVAC system or to an intermediate auxiliary HVACcontrol unit is described. The thermostat includes: a plurality ofwiring terminals each adapted to make electrical connection with one ofa plurality of control wires running between a first location where thethermostat is installed and a second location where an HVAC system isinstalled; and processors and circuitry configured and programmed tocommunicate with an auxiliary unit if installed at the second locationvia one or more of the plurality of control wires connected to one ormore of the wiring terminals, the auxiliary unit being directlyelectrically connected to an installed HVAC system via a plurality ofHVAC control wires. The processors and circuitry are further configuredand programmed to control the HVAC system directly without an auxiliaryunit when the plurality of control wires are connected directly to boththe plurality of wiring terminals and to the HVAC system.

According to some embodiments the communication between the thermostatand the auxiliary unit is bi-directional. According to some embodiments,automatic detection of connection to an auxiliary unit is provided, forexample based on an assessment of which of the one or more wiringterminals have wires connected thereto. When the connection to anauxiliary unit is detected the wires are automatically re-purposes tocommunicate with and receive electrical power from an auxiliary unit.

According to some embodiments the auxiliary unit is mounted in closeproximity (e.g. within 5 meters) of an air mover or furnace of the HVACsystem, and may be directly on a housing of the air mover or furnace.The number of wires used for connection between the wiring terminals andthe auxiliary unit, is preferably substantially fewer than would be usedfor a connection from the wiring terminals directly to the HVAC system.According to some embodiments only 3 or 4 wires are used to interconnectthe thermostat to the auxiliary unit. According to some embodiments, theauxiliary unit is capable of controlling an HVAC system having variablefan speed using a pulse-width-modulated control signal. The thermostatwhen mounted on a wall preferably occupies no more than 100 squarecentimeters, and the plurality of wiring terminals are configured fortool-free wire connection.

According to some embodiments, an auxiliary HVAC control unit forcontrolling an HVAC system is described. The unit includes: a first setof wiring terminals each adapted to make electrical connection with oneof a first plurality wires running between a first location where athermostat is installed and a second location where the auxiliary unitthe HVAC system is installed; a second set of wiring terminals eachadapted to make electrical connection with one of second plurality ofwires running between the auxiliary unit and the HVAC system; and agraphic display visible to a human viewing the display, the displayindicating to the human which of the second set of wiring terminals arecurrently electrically connected to each other.

According to some embodiments the unit also includes a plurality ofrelays used to open and close connections between conductors leading tothe second set of wiring terminals, and the graphic display includes aplurality of visible LEDs that indicate status of one or more of therelays. According to some embodiments, the auxiliary unit can connect toone or more wires leading to one or more remote temperature sensors(such as an outdoor air temperature, indoor air temperature, and/orreturn air temperature).

It will be appreciated that these systems and methods are novel, as areapplications thereof and many of the components, systems, methods andalgorithms employed and included therein. It should be appreciated thatembodiments of the presently described inventive body of work can beimplemented in numerous ways, including as processes, apparata, systems,devices, methods, computer readable media, computational algorithms,embedded or distributed software and/or as a combination thereof.Several illustrative embodiments are described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive body of work will be readily understood by referring tothe following detailed description in conjunction with the accompanyingdrawings, in which:

FIG. 1 illustrates an example of a smart home environment within whichone or more of the devices, methods, systems, services, and/or computerprogram products described further herein can be applicable;

FIG. 2 illustrates a network-level view of an extensible devices andservices platform with which the smart home of FIG. 1 can be integrated,according to some embodiments;

FIG. 3 illustrates an abstracted functional view of the extensibledevices and services platform of FIG. 2, according to some embodiments;

FIG. 4A is a schematic diagram of an HVAC system connected directly to athermostat, according to some embodiments;

FIG. 4B is a schematic diagram of an HVAC system being controlled by athermostat through an auxiliary HVAC control unit, according to someembodiments;

FIGS. 5A-5E illustrate a thermostat having a visually pleasing, smooth,sleek and rounded exterior appearance while at the same time includingone or more sensors for detecting occupancy and/or users, according tosome embodiments;

FIG. 6 is a schematic diagram showing electronic circuitry within anAHCU, according to some embodiments;

FIG. 7 is a perspective view of an auxiliary HVAC control unit whichincludes a graphical representation wiring and operation presented as a“train map” type diagram, according to some embodiments;

FIGS. 8A-8B are schematic diagrams showing aspects of circuitry in anauxiliary HVAC control unit for receiving and sending messages from andto a thermostat, according to some embodiments;

FIG. 8C is a schematic diagram showing aspects of circuitry within anauxiliary HVAC control unit for sending variable fan speed signal to anHVAC system, according to some embodiments;

FIG. 8D is a schematic diagram showing aspects of circuitry within anAHCU for detecting a reset signal, according to some embodiments; and

FIG. 9 shows an example of a thermostat connected to a cascadedarrangement of multiple auxiliary control units configured to controldifferent types of smart home equipment, according to some embodiments.

DETAILED DESCRIPTION

The subject matter of this patent specification relates to the subjectmatter of the following commonly assigned applications, each of which isincorporated by reference herein: U.S. Ser. No. 13/034,666 filed Feb.24, 2011; and International Application Ser. No. PCT/US12/00007 filedJan. 3, 2012. The above-referenced patent applications are collectivelyreferenced herein as “the commonly assigned incorporated applications.”

A detailed description of the inventive body of work is provided herein.While several embodiments are described, it should be understood thatthe inventive body of work is not limited to any one embodiment, butinstead encompasses numerous alternatives, modifications, andequivalents. In addition, while numerous specific details are set forthin the following description in order to provide a thoroughunderstanding of the inventive body of work, some embodiments can bepracticed without some or all of these details. Moreover, for thepurpose of clarity, certain technical material that is known in therelated art has not been described in detail in order to avoidunnecessarily obscuring the inventive body of work.

As used herein the term “HVAC” includes systems providing both heatingand cooling, heating only, cooling only, as well as systems that provideother occupant comfort and/or conditioning functionality such ashumidification, dehumidification and ventilation.

As used herein the terms power “harvesting,” “sharing” and “stealing”when referring to HVAC thermostats all refer to thermostats that aredesigned to derive power from the power transformer through theequipment load without using a direct or common wire source directlyfrom the transformer.

As used herein the term “residential” when referring to an HVAC systemmeans a type of HVAC system that is suitable to heat, cool and/orotherwise condition the interior of a building that is primarily used asa single family dwelling. An example of a cooling system that would beconsidered residential would have a cooling capacity of less than about5 tons of refrigeration (1 ton of refrigeration=12,000 Btu/h).

As used herein the term “light commercial” when referring to an HVACsystem means a type of HVAC system that is suitable to heat, cool and/orotherwise condition the interior of a building that is primarily usedfor commercial purposes, but is of a size and construction that aresidential HVAC system is considered suitable. An example of a coolingsystem that would be considered residential would have a coolingcapacity of less than about 5 tons of refrigeration.

As used herein the term “thermostat” means a device or system forregulating parameters such as temperature and/or humidity within atleast a part of an enclosure. The term “thermostat” may include acontrol unit for a heating and/or cooling system or a component part ofa heater or air conditioner. As used herein the term “thermostat” canalso refer generally to a versatile sensing and control unit (VSCU unit)that is configured and adapted to provide sophisticated, customized,energy-saving HVAC control functionality while at the same time beingvisually appealing, non-intimidating, elegant to behold, anddelightfully easy to use.

FIG. 1 illustrates an example of a smart home environment within whichone or more of the devices, methods, systems, services, and/or computerprogram products described further herein can be applicable. Thedepicted smart home environment includes a structure 150, which caninclude, e.g., a house, office building, garage, or mobile home. It willbe appreciated that devices can also be integrated into a smart homeenvironment that does not include an entire structure 150, such as anapartment, condominium, or office space. Further, the smart homeenvironment can control and/or be coupled to devices outside of theactual structure 150. Indeed, several devices in the smart homeenvironment need not physically be within the structure 150 at all. Forexample, a device controlling a pool heater or irrigation system can belocated outside of the structure 150.

The depicted structure 150 includes a plurality of rooms 152, separatedat least partly from each other via walls 154. The walls 154 can includeinterior walls or exterior walls. Each room can further include a floor156 and a ceiling 158. Devices can be mounted on, integrated with and/orsupported by a wall 154, floor or ceiling.

The smart home depicted in FIG. 1 includes a plurality of devices,including intelligent, multi-sensing, network-connected devices that canintegrate seamlessly with each other and/or with cloud-based serversystems to provide any of a variety of useful smart home objectives.One, more or each of the devices illustrated in the smart homeenvironment and/or in the figure can include one or more sensors, a userinterface, a power supply, a communications component, a modularity unitand intelligent software as described herein. Examples of devices areshown in FIG. 1.

An intelligent, multi-sensing, network-connected thermostat 102 candetect ambient climate characteristics (e.g., temperature and/orhumidity) and control a heating, ventilation and air-conditioning (HVAC)system 103. One or more intelligent, network-connected, multi-sensinghazard detection units 104 can detect the presence of a hazardoussubstance and/or a hazardous condition in the home environment (e.g.,smoke, fire, or carbon monoxide). One or more intelligent,multi-sensing, network-connected entryway interface devices 106, whichcan be termed a “smart doorbell”, can detect a person's approach to ordeparture from a location, control audible functionality, announce aperson's approach or departure via audio or visual means, or controlsettings on a security system (e.g., to activate or deactivate thesecurity system).

Each of a plurality of intelligent, multi-sensing, network-connectedwall light switches 108 can detect ambient lighting conditions, detectroom-occupancy states and control a power and/or dim state of one ormore lights. In some instances, light switches 108 can further oralternatively control a power state or speed of a fan, such as a ceilingfan. Each of a plurality of intelligent, multi-sensing,network-connected wall plug interfaces 110 can detect occupancy of aroom or enclosure and control supply of power to one or more wall plugs(e.g., such that power is not supplied to the plug if nobody is athome). The smart home may further include a plurality of intelligent,multi-sensing, network-connected appliances 112, such as refrigerators,stoves and/or ovens, televisions, washers, dryers, lights (inside and/oroutside the structure 150), stereos, intercom systems, garage-dooropeners, floor fans, ceiling fans, whole-house fans, wall airconditioners, pool heaters 114, irrigation systems 116, security systems(including security system components such as cameras, motion detectorsand window/door sensors), and so forth. While descriptions of FIG. 1 canidentify specific sensors and functionalities associated with specificdevices, it will be appreciated that any of a variety of sensors andfunctionalities (such as those described throughout the specification)can be integrated into the device.

In addition to containing processing and sensing capabilities, each ofthe devices 102, 104, 106, 108, 110, 112, 114 and 116 can be capable ofdata communications and information sharing with any other of thedevices 102, 104, 106, 108, 110, 112, 114 and 116, as well as to anycloud server or any other device that is network-connected anywhere inthe world. The devices can send and receive communications via any of avariety of custom or standard wireless protocols (Wi-Fi, ZigBee,6LoWPAN, etc.) and/or any of a variety of custom or standard wiredprotocols (CAT6 Ethernet, HomePlug, etc.). The wall plug interfaces 110can serve as wireless or wired repeaters, and/or can function as bridgesbetween (i) devices plugged into AC outlets and communicating usingHomeplug or other power line protocol, and (ii) devices that not pluggedinto AC outlets.

For example, a first device can communicate with a second device via awireless router 160. A device can further communicate with remotedevices via a connection to a network, such as the Internet 162. Throughthe Internet 162, the device can communicate with a central server or acloud-computing system 164. The central server or cloud-computing system164 can be associated with a manufacturer, support entity or serviceprovider associated with the device. For one embodiment, a user may beable to contact customer support using a device itself rather thanneeding to use other communication means such as a telephone orInternet-connected computer. Further, software updates can beautomatically sent from the central server or cloud-computing system 164to devices (e.g., when available, when purchased, or at routineintervals).

By virtue of network connectivity, one or more of the smart-home devicesof FIG. 1 can further allow a user to interact with the device even ifthe user is not proximate to the device. For example, a user cancommunicate with a device using a computer (e.g., a desktop computer,laptop computer, or tablet) or other portable electronic device (e.g., asmartphone). A webpage or app can be configured to receivecommunications from the user and control the device based on thecommunications and/or to present information about the device'soperation to the user. For example, the user can view a current setpointtemperature for a device and adjust it using a computer. The user can bein the structure during this remote communication or outside thestructure.

The smart home also can include a variety of non-communicating legacyappliances 140, such as old conventional washer/dryers, refrigerators,and the like which can be controlled, albeit coarsely (ON/OFF), byvirtue of the wall plug interfaces 110. The smart home can furtherinclude a variety of partially communicating legacy appliances 142, suchas IR-controlled wall air conditioners or other IR-controlled devices,which can be controlled by IR signals provided by the hazard detectionunits 104 or the light switches 108.

FIG. 2 illustrates a network-level view of an extensible devices andservices platform with which the smart home of FIG. 1 can be integrated,according to some embodiments. Each of the intelligent,network-connected devices from FIG. 1 can communicate with one or moreremote central servers or cloud computing systems 164. The communicationcan be enabled by establishing connection to the Internet 162 eitherdirectly (for example, using 3G/4G connectivity to a wireless carrier),though a hubbed network (which can be scheme ranging from a simplewireless router, for example, up to and including an intelligent,dedicated whole-home control node), or through any combination thereof.

The central server or cloud-computing system 164 can collect operationdata 202 from the smart home devices. For example, the devices canroutinely transmit operation data or can transmit operation data inspecific instances (e.g., when requesting customer support). The centralserver or cloud-computing architecture 164 can further provide one ormore services 204. The services 204 can include, e.g., software update,customer support, sensor data collection/logging, remote access, remoteor distributed control, or use suggestions (e.g., based on collectedoperation data 204 to improve performance, reduce utility cost, etc.).Data associated with the services 204 can be stored at the centralserver or cloud-computing system 164 and the central server orcloud-computing system 164 can retrieve and transmit the data at anappropriate time (e.g., at regular intervals, upon receiving requestfrom a user, etc.).

One salient feature of the described extensible devices and servicesplatform, as illustrated in FIG. 2, is a processing engines 206, whichcan be concentrated at a single server or distributed among severaldifferent computing entities without limitation. Processing engines 206can include engines configured to receive data from a set of devices(e.g., via the Internet or a hubbed network), to index the data, toanalyze the data and/or to generate statistics based on the analysis oras part of the analysis. The analyzed data can be stored as derived data208. Results of the analysis or statistics can thereafter be transmittedback to a device providing ops data used to derive the results, to otherdevices, to a server providing a webpage to a user of the device, or toother non-device entities. For example, use statistics, use statisticsrelative to use of other devices, use patterns, and/or statisticssummarizing sensor readings can be transmitted. The results orstatistics can be provided via the Internet 162. In this manner,processing engines 206 can be configured and programmed to derive avariety of useful information from the operational data obtained fromthe smart home. A single server can include one or more engines.

The derived data can be highly beneficial at a variety of differentgranularities for a variety of useful purposes, ranging from explicitprogrammed control of the devices on a per-home, per-neighborhood, orper-region basis (for example, demand-response programs for electricalutilities), to the generation of inferential abstractions that canassist on a per-home basis (for example, an inference can be drawn thatthe homeowner has left for vacation and so security detection equipmentcan be put on heightened sensitivity), to the generation of statisticsand associated inferential abstractions that can be used for governmentor charitable purposes. For example, processing engines 206 can generatestatistics about device usage across a population of devices and sendthe statistics to device users, service providers or other entities(e.g., that have requested or may have provided monetary compensationfor the statistics). As specific illustrations, statistics can betransmitted to charities 222, governmental entities 224 (e.g., the Foodand Drug Administration or the Environmental Protection Agency),academic institutions 226 (e.g., university researchers), businesses 228(e.g., providing device warranties or service to related equipment), orutility companies 230. These entities can use the data to form programsto reduce energy usage, to preemptively service faulty equipment, toprepare for high service demands, to track past service performance,etc., or to perform any of a variety of beneficial functions or tasksnow known or hereinafter developed.

FIG. 3 illustrates an abstracted functional view of the extensibledevices and services platform of FIG. 2, with particular reference tothe processing engine 206 as well as the devices of the smart home. Eventhough the devices situated in the smart home will have an endlessvariety of different individual capabilities and limitations, they canall be thought of as sharing common characteristics in that each of themis a data consumer 302 (DC), a data source 304 (DS), a services consumer306 (SC), and a services source 308 (SS). Advantageously, in addition toproviding the essential control information needed for the devices toachieve their local and immediate objectives, the extensible devices andservices platform can also be configured to harness the large amount ofdata that is flowing out of these devices. In addition to enhancing oroptimizing the actual operation of the devices themselves with respectto their immediate functions, the extensible devices and servicesplatform can also be directed to “repurposing” that data in a variety ofautomated, extensible, flexible, and/or scalable ways to achieve avariety of useful objectives. These objectives may be predefined oradaptively identified based on, e.g., usage patterns, device efficiency,and/or user input (e.g., requesting specific functionality).

For example, FIG. 3 shows processing engine 206 as including a number ofparadigms 310. Processing engine 206 can include a managed servicesparadigm 310 a that monitors and manages primary or secondary devicefunctions. The device functions can include ensuring proper operation ofa device given user inputs, estimating that (e.g., and responding to) anintruder is or is attempting to be in a dwelling, detecting a failure ofequipment coupled to the device (e.g., a light bulb having burned out),implementing or otherwise responding to energy demand response events,or alerting a user of a current or predicted future event orcharacteristic. Processing engine 206 can further include anadvertising/communication paradigm 310 b that estimates characteristics(e.g., demographic information), desires and/or products of interest ofa user based on device usage. Services, promotions, products or upgradescan then be offered or automatically provided to the user. Processingengine 206 can further include a social paradigm 310 c that usesinformation from a social network, provides information to a socialnetwork (for example, based on device usage), processes data associatedwith user and/or device interactions with the social network platform.For example, a user's status as reported to their trusted contacts onthe social network could be updated to indicate when they are home basedon light detection, security system inactivation or device usagedetectors. As another example, a user may be able to share device-usagestatistics with other users. Processing engine 206 can include achallenges/rules/compliance/rewards paradigm 310 d that informs a userof challenges, rules, compliance regulations and/or rewards and/or thatuses operation data to determine whether a challenge has been met, arule or regulation has been complied with and/or a reward has beenearned. The challenges, rules or regulations can relate to efforts toconserve energy, to live safely (e.g., reducing exposure to toxins orcarcinogens), to conserve money and/or equipment life, to improvehealth, etc.

Processing engine can integrate or otherwise utilize extrinsicinformation 316 from extrinsic sources to improve the functioning of oneor more processing paradigms. Extrinsic information 316 can be used tointerpret operational data received from a device, to determine acharacteristic of the environment near the device (e.g., outside astructure that the device is enclosed in), to determine services orproducts available to the user, to identify a social network orsocial-network information, to determine contact information of entities(e.g., public-service entities such as an emergency-response team, thepolice or a hospital) near the device, etc., to identify statistical orenvironmental conditions, trends or other information associated with ahome or neighborhood, and so forth.

An extraordinary range and variety of benefits can be brought about by,and fit within the scope of, the described extensible devices andservices platform, ranging from the ordinary to the profound. Thus, inone “ordinary” example, each bedroom of the smart home can be providedwith a smoke/fire/CO alarm that includes an occupancy sensor, whereinthe occupancy sensor is also capable of inferring (e.g., by virtue ofmotion detection, facial recognition, audible sound patterns, etc.)whether the occupant is asleep or awake. If a serious fire event issensed, the remote security/monitoring service or fire department isadvised of how many occupants there are in each bedroom, and whetherthose occupants are still asleep (or immobile) or whether they haveproperly evacuated the bedroom. While this is, of course, a veryadvantageous capability accommodated by the described extensible devicesand services platform, there can be substantially more “profound”examples that can truly illustrate the potential of a larger“intelligence” that can be made available. By way of perhaps a more“profound” example, the same data bedroom occupancy data that is beingused for fire safety can also be “repurposed” by the processing engine206 in the context of a social paradigm of neighborhood childdevelopment and education. Thus, for example, the same bedroom occupancyand motion data discussed in the “ordinary” example can be collected andmade available for processing (properly anonymized) in which the sleeppatterns of schoolchildren in a particular ZIP code can be identifiedand tracked. Localized variations in the sleeping patterns of theschoolchildren may be identified and correlated, for example, todifferent nutrition programs in local schools.

FIG. 4A is a schematic diagram of an HVAC system connected directly to athermostat 102, according to some embodiments. HVAC system 103 providesheating, cooling, ventilation, and/or air handling for an enclosure,such as structure 150 depicted in FIG. 1. System 103 depicts a forcedair type heating and cooling system, although according to otherembodiments, other types of HVAC systems could be used such as radiantheat based systems, heat-pump based systems, and others.

For carrying out the heating function, heating coils or elements 442within air handler 440 provide a source of heat using electricity or gasvia line 436. Cool air is drawn from the enclosure via return air duct446 through filter 470, using fan 438 and is heated through heatingcoils or elements 442. The heated air flows back into the enclosure atone or more locations via supply air duct system 452 and supply airregisters such as register 450. In cooling, an outside compressor 430passes a refrigerant gas through a set of heat exchanger coils and thenthrough an expansion valve. The gas then goes through line 432 to thecooling coils or evaporator coils 434 in the air handler 440 where itexpands, cools and cools the air being circulated via fan 438. Ahumidifier 454 may optionally be included in various embodiments thatreturns moisture to the air before it passes through duct system 452.Although not shown in FIG. 4A, alternate embodiments of HVAC system 103may have other functionality such as venting air to and from theoutside, one or more dampers to control airflow within the duct system452 and an emergency heating unit. Overall operation of HVAC system 103is selectively actuated by control electronics 412 communicatingdirectly with thermostat 102 using a number of wires 448. The number ofcontrol wires depends on what types of components are included HVACsystem 103, ranging from 2 wires for a basic single stage heating HVACsystem to up to 8 or 10 wires 448 in the case of more complex systems.

FIG. 4B is a schematic diagram of an HVAC system 103A being controlledby thermostat 102 through an auxiliary HVAC control unit, according tosome embodiments. In this case the thermostat 102 is connected to theauxiliary HVAC control unit (AHCU) 460 via a small number of (forexample 3 or 4) wires 480 and the AHCU 460 is connected to the HVACsystem using a larger number of wires (for example up to 16) 490, toHVAC system 103A via the HVAC control electronics 412. Note that theHVAC system 103A can be identical or similar to HVAC system 103, or itcould be considerably more complex, making use of many more wires forcontrolling. According to some embodiments, AHCU 460 can accept up to 22wires 490 for connection to HVAC system 103A. Examples of wires 490between the AHCU and HVAC system 103A include the following: “Rh” (Power24VAC); “Rc” (Power 24VAC); “C” (Power 24VAC, Typically Earth GND); “W1”(First Stage Heat, Return to Rh); “6” (Heating Zones 1-3, power to closevalve, Return to Rh); “W2” (Second Stage Heat, Return to Rh); “W3/AUX/E”(Third Stage Heat, Return to Rh); “G” (Fan, Return to Rh); “Y1” (FirstStage Cooling, or Heat Pump Enable, Return to Rc); “Y2” (Second StageCooling, Return to Rc); “O/B” (Heat Pump Direction, Return to Rc);“HUM1” (Humidifier, Returns to HUM2 or to Rc/Rh); “HUM2” (Second StageHumidifier, or return for HUM1); “HUM3” (Second Stage Humidifier, orreturn for HUM1 and/or HUM2); “DEH1” (Dehumidifier, Returns to DEH2 orto Rc/Rh); “DEH2” (Second Stage Dehumidifier, or return for DEH1);“DEH2” (Second Stage Dehumidifier, or return for DEH1 and/or DEH2) “L”(Fault Lamp, for signaling an HVAC fault back to the thermostat); and“V” (Variable speed fan). According to some embodiments the AHCU canalso be used to communicate with a number of additional sensors, such asoutdoor temperature sensor 472 connected via wire 482 and return airtemperature sensor 474 via wire 484, located in return air duct 446.Note that the AHCU 460 is installed very close to the HVAC system. Forexample, it can be either affixed to the air mover and/or furnace ormounted onto a nearby wall. By locating the AHCU directly on or veryclose to the HVAC system furnace or air mover, and communicating andsupplying power to the thermostat 102 using only a few wires (e.g. 3 or4 wires 480), a sleek relatively small thermostat that is visuallypleasing when wall mounted in a home even with an HVAC system thatbenefits from a large number of wire connections.

Thus, as shown in FIGS. 4A and 4B, according to some embodiments, thesame thermostat unit 102 is capable of connecting either directly to anHVAC system in as in FIG. 4A, through an AHCU, as in FIG. 4B. Accordingto some embodiments, the thermostat 102 is capable of automaticallydetecting whether it is connected directly to an HVAC system or throughan AHCU. When connection to an AHCU is detected, the connected wires are“repurposed” to receive power from and communicate with the AHCU.

FIGS. 5A-5E illustrate a thermostat having a visually pleasing, smooth,sleek and rounded exterior appearance while at the same time includingone or more sensors for detecting occupancy and/or users, according tosome embodiments. FIG. 5A is front view, FIG. 5B is a bottom elevation,FIG. 5C is a right side elevation, and FIG. 5D is prospective view ofthermostat 102. Unlike many prior art thermostats, thermostat 102 has asleek, simple, uncluttered and elegant design that does not detract fromhome decoration, and indeed can serve as a visually pleasing centerpiecefor the immediate location in which it is installed. Moreover, userinteraction with thermostat 102 is facilitated and greatly enhanced overknown conventional thermostats by the design of thermostat 102. Thethermostat 102 includes control circuitry and is electrically connectedto an HVAC system 103, such as is shown in FIGS. 1-4. Thermostat 102 iswall mountable, is circular in shape, and has an outer rotatable ring512 for receiving user input. Thermostat 102 is circular in shape inthat it appears as a generally disk-like circular object when mounted onthe wall. Thermostat 102 has a large convex rounded front face lyinginside the outer ring 512. According to some embodiments, thermostat 102is approximately 80 mm in diameter and protrudes from the wall, whenwall mounted, by 32 mm. The outer rotatable ring 512 allows the user tomake adjustments, such as selecting a new setpoint temperature. Forexample, by rotating the outer ring 512 clockwise, the realtime (i.e.currently active) setpoint temperature can be increased, and by rotatingthe outer ring 512 counter-clockwise, the realtime setpoint temperaturecan be decreased. The front face of the thermostat 102 comprises a clearcover 514 that according to some embodiments is polycarbonate, and aFresnel lens 510 having an outer shape that matches the contours of thecurved outer front face of the thermostat 102. According to someembodiments, the Fresnel lens elements are formed on the interiorsurface of the Fresnel lens piece 510 such that they are not obviouslyvisible by viewing the exterior of the thermostat 102. Behind theFresnel lens is a passive infrared sensor 550 for detecting occupancy,and the Fresnel lens piece 510 is made from a high-density polyethylene(HDPE) that has an infrared transmission range appropriate forsensitivity to human bodies. As shown in FIGS. 5A-5D, the front edge ofrotating ring 512, front face 514 and Fresnel lens 510 are shaped suchthat they together form a, integrated convex rounded front face that hasa common outward arc or spherical shape gently arcing outward.

Although being formed from a single lens-like piece of material such aspolycarbonate, the cover 514 has two different regions or portionsincluding an outer portion 514 o and a central portion 514 i. Accordingto some embodiments, the cover 514 is painted or smoked around the outerportion 514 o, but leaves the central portion 514 i visibly clear so asto facilitate viewing of an electronic display 516 disposedthereunderneath. According to some embodiments, the curved cover 514acts as a lens that tends to magnify the information being displayed inelectronic display 516 to users. According to some embodiments thecentral electronic display 516 is a dot-matrix layout (i.e. individuallyaddressable) such that arbitrary shapes can be generated, rather thanbeing a segmented layout. According to some embodiments, a combinationof dot-matrix layout and segmented layout is employed. According to someembodiments, central display 516 is a backlit color liquid crystaldisplay (LCD). According to some embodiments another phase-change baseddisplay could be used, such as electronic paper or e-ink for centraldisplay 516. An example of information displayed on the electronicdisplay 516 is illustrated in FIG. 5A, and includes central numerals 520that are representative of a current setpoint temperature. Thethermostat 102 is preferably constructed such that the electronicdisplay 516 is at a fixed orientation and does not rotate with the outerring 512, so that the electronic display 516 remains easily read by theuser. For some embodiments, the cover 514 and Fresnel lens 510 alsoremain at a fixed orientation and do not rotate with the outer ring 512.According to one embodiment in which the diameter of the thermostat 102is about 80 mm, the diameter of the electronic display 516 is about 45mm. According to some embodiments the gently outwardly curved shape ofthe front surface of thermostat 102, which is made up of cover 514,Fresnel lens 510 and the front facing portion of ring 512, is spherical,and matches a sphere having a radius of between 100 mm and 150 mm.According to some embodiments, the radius of the spherical shape of thethermostat front is about 136 mm.

Motion sensing with PIR sensor 550 as well as other techniques can beused in the detection and/or predict of occupancy, as is describedfurther in the commonly assigned U.S. patent application Ser. No.12/881,430, which is incorporated herein by reference. According to someembodiments, occupancy information is used in generating an effectiveand efficient scheduled program. A second downwardly-tilted PIR sensor552 is provided to detect an approaching user. The proximity sensor 552can be used to detect proximity in the range of about one meter so thatthe thermostat 102 can initiate “waking up” when the user is approachingthe thermostat and prior to the user touching the thermostat. Such useof proximity sensing is useful for enhancing the user experience bybeing “ready” for interaction as soon as, or very soon after the user isready to interact with the thermostat. Further, the wake-up-on-proximityfunctionality also allows for energy savings within the thermostat by“sleeping” when no user interaction is taking place our about to takeplace.

According to some embodiments, for the combined purposes of inspiringuser confidence and further promoting visual and functional elegance,the thermostat 102 is controlled by only two types of user input, thefirst being a rotation of the outer ring 512 as shown in FIG. 5A(referenced hereafter as a “rotate ring” or “ring rotation” input), andthe second being an inward push on head unit 540 until an audible and/ortactile “click” occurs (referenced hereafter as an “inward click” orsimply “click” input). For such embodiments, the head unit 540 is anassembly that includes all of the outer ring 512, cover 514, electronicdisplay 516, and the Fresnel lens 510. When pressed inwardly by theuser, the head unit 540 travels inwardly by a small amount, such as 0.5mm, against an interior metallic dome switch (not shown), and thenspringably travels back outwardly by that same amount when the inwardpressure is released, providing a satisfying tactile “click” sensationto the user's hand, along with a corresponding gentle audible clickingsound. According to some embodiments, the clicking sound is generated bya small speaker located within the thermostat 102. Thus, for theembodiment of FIGS. 5A-5D, an inward click can be achieved by directpressing on the outer ring 512 itself, or by indirect pressing of theouter ring by virtue of providing inward pressure on the cover 514, lens510, or by various combinations thereof. For other embodiments, thethermostat 102 can be mechanically configured such that only the outerring 512 travels inwardly for the inward click input, while the cover514 and lens 510 remain motionless. It is to be appreciated that avariety of different selections and combinations of the particularmechanical elements that will travel inwardly to achieve the “inwardclick” input are within the scope of the present teachings, whether itbe the outer ring 512 itself, some part of the cover 514, or somecombination thereof. However, it has been found particularlyadvantageous to provide the user with an ability to quickly go back andforth between registering “ring rotations” and “inward clicks” with asingle hand and with minimal amount of time and effort involved, and sothe ability to provide an inward click directly by pressing the outerring 512 has been found particularly advantageous, since the user'sfingers do not need to be lifted out of contact with the device, or slidalong its surface, in order to go between ring rotations and inwardclicks. Moreover, by virtue of the strategic placement of the electronicdisplay 516 centrally inside the rotatable ring 512, a further advantageis provided in that the user can naturally focus their attention on theelectronic display throughout the input process, right in the middle ofwhere their hand is performing its functions. The combination ofintuitive outer ring rotation, especially as applied to (but not limitedto) the changing of a thermostat's setpoint temperature, convenientlyfolded together with the satisfying physical sensation of inwardclicking, together with accommodating natural focus on the electronicdisplay in the central midst of their fingers' activity, addssignificantly to an intuitive, seamless, and downright fun userexperience. Further descriptions of advantageous mechanicaluser-interfaces and related designs, which are employed according tosome embodiments, can be found in U.S. Ser. No. 13/033,573, U.S. Ser.No. 29/386,021, and U.S. Ser. No. 13/199,108, all of which areincorporated herein by reference.

FIGS. 5B and 5C are bottom and right side elevation views of thethermostat 102, which has been found to provide a particularly pleasingand adaptable visual appearance when viewed against a variety ofdifferent wall colors and wall textures in a variety of different homeenvironments and home settings. While the thermostat itself willfunctionally adapt to the user's schedule as described herein and in oneor more of the commonly assigned incorporated applications, the outershape is specially configured to convey a “chameleon” quality orcharacteristic such that the overall device appears to naturally blendin, in a visual and decorative sense, with many of the most common wallcolors and wall textures found in home and business environments, atleast in part because it will appear to assume the surrounding colorsand even textures when viewed from many different angles.

According to some embodiments, the thermostat 102 includes a processingsystem 560, display driver 564 and a wireless communications system 566.The processing system 560 is adapted to cause the display driver 564 anddisplay 516 to display information to the user, and to receiver userinput via the rotatable ring 512. The processing system 560, accordingto some embodiments, is capable of carrying out the governance of theoperation of thermostat 102 including various user interface features.The processing system 560 is further programmed and configured to carryout other operations as described further hereinbelow and/or in otherones of the commonly assigned incorporated applications. For example,processing system 560 is further programmed and configured to maintainand update a thermodynamic model for the enclosure in which the HVACsystem is installed, such as described in U.S. Ser. No. 12/881,463, andin International Patent App. No. PCT/US11/51579, both of which areincorporated herein by reference. According to some embodiments, thewireless communications system 566 is used to communicate with devicessuch as personal computers and/or other thermostats or HVAC systemcomponents, which can be peer-to-peer communications, communicationsthrough one or more servers located on a private network, or and/orcommunications through a cloud-based service.

According to some embodiments, for ease of installation, configurationand/or upgrading, especially by a non-expert installer such as a user,the thermostat 102 includes a head unit 540 and a backplate (or walldock) 542. As is described hereinabove, thermostat 102 is wall mountedand has circular in shape and has an outer rotatable ring 512 forreceiving user input. Head unit 540 of thermostat 102 is slidablymountable onto back plate 542 and slidably detachable therefrom, asshown in FIG. 5E, which depicts the backplate 542 mounted on a wall withthe headunit 540 removed. According to some embodiments the connectionof the head unit 540 to backplate 542 can be accomplished using magnets,bayonet, latches and catches, tabs or ribs with matching indentations,or simply friction on mating portions of the head unit 540 and backplate542. According to some embodiments, the head unit 540 includes aprocessing system 560, display driver 564 and a wireless communicationssystem 566. Also shown is a rechargeable battery 522 that is rechargedusing recharging circuitry 524 that uses power from backplate that iseither obtained via power harvesting (also referred to as power stealingand/or power sharing) from the HVAC system control circuit(s) or from acommon wire, if available, as described in further detail in co-pendingpatent application U.S. Ser. Nos. 13/034,674, and 13/034,678, which areincorporated by reference herein. According to some embodiments,rechargeable battery 522 is a single cell lithium-ion, or alithium-polymer battery.

Also visible in FIG. 5E are plurality of tool-free wiring terminals 550,each adapted and configured to make an electrical connection with anHVAC wire. Each of the wiring terminals 550 are adapted and configuredto allow a user to make an electrical connection with an HVAC wirewithout the use of tools by pressing a button member and inserting anHVAC wire into a wire hole. While there is substantial benefit inproviding such tool-free wiring terminals, they generally take up agreater amount of space on backplate 542 than would screw-type wiringterminals. Additionally, as described, infra, the thermostat 102 isabout 80 mm in diameter according to some embodiment, and therefore thebackplate 541 is less than that dimension. As such there is asubstantial benefit to using an AHCU since only a limited number of toolfree wiring terminals can be accommodated on such a small backplate. Inthe case where thermostat 102 is connected to an AHCU instead ofdirectly to the HVAC system wires, the wiring terminals 550 are alsoused for making connection to the AHCU wires. Since generally only asmall number of wires will be used in communicating and receiving powerfrom the AHCU, only a subset of the wiring terminals 550 will be used(note that in the embodiment shown in FIG. 5E, backplate 542 includes 10wiring terminals arranged in two circular arc-shaped banks). Shown inFIG. 5E are four AHCU wires 480 passing through a hole in the wall andeach connected to the wiring terminals 550. According to someembodiments, only three wires are used to connect thermostat 102 to theAHCU 460. In the three-wire case, the wiring terminals for the “C” and“Rc” wires are used to receive power from the AHCU, and wiring terminalfor an “O/B” wire is used for serial communication. According to someother embodiments, four wires are used to connect thermostat 102 to theAHCU 460. In a four-wire configuration, an additional communication wireis used which is connected to the “W1” wiring terminal on thermostat102. Note that in these embodiments, auto detection of connection to anAHCU is very straightforward since direct connection to an HVAC systemwill never include an O/B wire (heat pump polarity) without anaccompanying “Y” wire attached. Thus, if the O/B wire is connected andthere is no Y wire connected, the thermostat 102 assumes it is connectedto an AHCU rather than directly to an HVAC system. In such cases, theconnected wires (i.e. the C, Rc, O/B and possibly the W1 wires) are“repurposed” to receive power (using the C and Rc wires) from andcommunicate (using either O/B wire alone or both the O/B and W1 wires)with the AHCU. According to some embodiments, other combinations of wireconnections can be used to both connect the AHCU 460 to thermostat 102as well as by the thermostat 102 to automatically detect a connection toan AHCU and automatically repurpose the wires.

FIG. 6 is a schematic diagram showing electronic circuitry within anAHCU, according to some embodiments. ACHU 460, is an external accessorythat is connected between the thermostat 102 and the HVAC system 103A.The ACHU 460 expands the number of HVAC wire switching circuits, andadds remote temperature sensing, fault reporting as well as support formodulating fan speed. Advantageously, this added functionality can begained without upgrading or changing the thermostat unit 102. Thus, theACHU is beneficial in expanding the compatibility of thermostat 102 to agreater variety of HVAC systems.

Additionally, no hardware change is required to the thermostat 102 toutilize the ACHU. All switching functions transfer from the backplate542 of the thermostat 102 to standard dry-contact relays in 650 on ACHU460. In this way, compatibility can be expanded since the HVAC system103A “sees” exactly the same interface (i.e conventional dry-contactrelays) as if it were connected to a standard conventional thermostat,and at the same time, the thermostat 102 is isolated from the HVACsignals, and always has power without the use of power stealing.

As described, infra, the ACHU 460 is configured for installation at theHVAC system, either affixed to the air mover/furnace or to a nearby wall(using wall mounting holes, not shown). Since as many as 22 wires can beconnected between the ACHU 460 and the HVAC system 103A, positioningbetween the HVAC system and the ACHU is beneficial. Additional wires caneasily be run between the HVAC system and the ACHU due to their closeproximity. Additionally, by affixing the ACHU directly to the air moverand/or furnace, or placing it on a nearby wall, the ACHU as well as themany wires running between the ACHU and the HVAC system has little or nonegative impact on the home's décor, thereby providing for a visuallypleasing installation.

As shown in FIG. 6, connection to the thermostat is via wiring terminals620 for power, and 622 for communication. According to some embodiments,the thermostat power is supplied in a way that simplifies the datainterface. In particular, the 24V AC signal is rectified to DC, (at˜35V), by switcher 621 and passed through a current limiting circuit orresetable fuse (at ∫100 mA) for safety (not shown). According to someembodiments, communication with the thermostat 102 uses the O/B wire,referenced from the C wire. According to some embodiments a singlededicated communication is used with a return and can be shared with thepower supply wires. The resulting current loop is used for asynchronous,interrupt driven serial communication. In a simple example, thethermostat sends a “give me second stage heat” and AHCU sends messageback “confirm second stage heat activated.” The communication can beeither bi-directional or unidirectional. According to some otherembodiments, the W1 wire between the AHCU and the thermostat is used forcommunication as well as the O/B wire, for a total of four wires usedbetween the thermostat and the AHCU.

According to some embodiments, a second thermostat can be attached tothe ACHU using terminals 624 (for communication) and 620 for power. Thismight be useful, for example, to attach a thermostat temporarily duringinstallation, diagnostics, and/or trouble shooting by connected anadditional thermostat locally directly to the ACHU. As will be describedin greater detail with respect to FIG. 7, supra, according to someembodiments a graphical representation of the ACHU wiring and operationis presented in which a painted or silkscreened diagram is providedalong with a number of LEDs to indicated various functions, operationsand connections taking place within the ACHU as a “train map” typediagram. The LEDs 626, 628, 652 and 654 shown in FIG. 6 are for thispurpose.

Also provided according to some embodiments is the ability by the AHCU460 to measure one or more additional temperature readings. Temperaturesensors can be connected to terminals 628 which lead to temperaturesense circuitry 630 as shown in FIG. 6. According to some embodiments,the temperature sensors can be for an outdoor air temperature (OAT)sensor, an indoor air temperature (IAT) sensor, and/or an return airtemperature (T RET) sensor.

Shown in FIG. 6 connection terminals 644 for a number of 24V HVAC wiresthat are used for connection to the HVAC system 103A. The C wireterminal 640, and the Rc wire terminal 642 (as well as the Rh terminalif a jumper is installed, as shown) are connection directly to the24VAC. The other terminals 644 include the following: “W1” (First StageHeat, Return to Rh); “6” (Heating Zones 1-3, power to close valve,Return to Rh); “W2” (Second Stage Heat, Return to Rh); “W3/AUX/E” (ThirdStage Heat, Return to Rh); “G” (Fan, Return to Rh); “Y1” (First StageCooling, or Heat Pump Enable, Return to Rc); “Y2” (Second Stage Cooling,Return to Rc); “O/B” (Heat Pump Direction, Return to Rc); “HUM1”(Humidifier, Returns to HUM2 or to Rc/Rh); “HUM2” (Second StageHumidifier, or return for HUM1); “HUM3” (Second Stage Humidifier, orreturn for HUM1 and/or HUM2); “DEH1” (Dehumidifier, Returns to DEH2 orto Rc/Rh); “DEH2” (Second Stage Dehumidifier, or return for DEH1);“DEH2” (Second Stage Dehumidifier, or return for DEH1 and/or DEH2).Terminals 646 are for an “L” wire (Fault Lamp, for signaling an HVACfault back to the thermostat); and a “V” wire (Variable speed fan).Terminals 648 are used for an RS-422 interface, which can replacemultiple wires and relays in some types of higher-end HVAC systems.

FIG. 7 is a perspective view of an AHCU which includes a graphicalrepresentation wiring and operation presented as a “train map” typediagram, according to some embodiments. The front panel 700 of AHCU 460is shown in FIG. 7 with the labels, circuit diagrams and symbolssilk-screened on the metallic (or other suitable housing material) outerhousing of AHCU 460. According to other embodiment a sticker or paintcan be used. The AHCU 460 front panel 700 also has a number of LEDspositioned to as to be visible and indicate various information to aperson viewing the front panel 700. For example a status LED 710 isshown in a “lit” state indicating the system is OK. Another LED is alsolit showing that the AHCU has power, in this case from the inserted Cwire (in the COM terminal) and an “Rh wire. AHCU 460 includes a numberof screw-anchored terminals 730 and 740 on either side of the housing,which are positioned as shown near the front panel 700 such that thesilk-screened labels and circuit lines can clearly associated with eachwire inserted in a terminal. In the case shown, four input wires 480inserted into wire terminals 730 running from the thermostat 102. TheLED 712 is lit, indicating that the connection to the thermostat 102 isfully operational. According to some embodiments, the LED 712 alsoindicate one or more error conditions, such as blinking at a slow orfast rate to indicate different problems. Any of the LEDs on the AHCU460 can also be configured to show two or more colors (such as green andamber) which can be used to indicate further information to a user (forthe thermostat link LED 712, for example, green sold could indicate andOK status, while blinking amber can indicate the wires are connected butthere is a problem). As described, infra, according to some embodiments,only three wires can be used, namely the Rc, O/B and C wires. Accordingto yet other embodiments, other numbers of wires can be used between theAHCU and the thermostat, for example greater numbers such as 5-8 wiresand fewer wires such as 2 wires can be used. Also shown are inputs 750for a second thermostat. As described, infra, attaching a thermostat tothe second input 750 temporarily right next to the AHCU 460 can beespecially useful during installation and/or diagnostic procedures sincea person could operate the thermostat and immediately see the resultingoperation of the AHCU 460 by viewing the front panel 700. Also shown inthis case are two wires 482 and 484 used to connect an outside airtemperature sensor and a return temperature sensor as shown in FIG. 4.LEDs 714 and 716 are lit showing that connection with those sensors isOK. A set of additional terminals 752 can be used, according to someembodiments for connection between AHCU and a device using RS-422standard signaling to send and/or receive data. For example, some HVACequipment may operate using RS-422 communication. According to someembodiment another cover piece that covers the all of the LEDs exceptfor LED 710 is provided so as to provide a more visually pleasingexterior in some settings.

Along the right side of the AHCU 460 are a number of terminals 740 usedto connected directly to an HVAC system. Shown in this example are inputterminals for 22 HVAC wires, although according to other embodimentsgreater or fewer numbers of terminals can be provided. The location ofthe input terminals is such that a person viewing front panel 700 caneasily and intuitively understand the internal connections between thevarious HVAC wires. For example, in the state shown in FIG. 7, it caneasily be understood by viewing the front panel 700 that an active firststage heating call is being made, since the W1 LED 722 and the Rh LED724 are both lit, and the circuit diagram shows that when those LEDs arelit there is a connection (or a short) between those two wires. Notethat in this case a jumper 728 is connected, which shorts the Rc and Rhterminals as indicated on front panel 700, and as a result, LED 726 isalso lit in the state shown. Thus, as shown, the “train map” stylegraphic display on front panel 700 of AHCU provides a graphicalindication to the installer or user as to which relays or switches arecurrently open and which are currently closed by the AHCU 460. It hasbeen found that a graphical display in this “train map” form is a usefulintuitive diagnostic tool for use during installation or otherdiagnostic procedures on the HVAC system.

According to some embodiments, firmware within the AHCU 460 isupgradeable from the thermostat 102. According to some otherembodiments, the AHCU 460 includes a wireless communication module 770,that uses a low power radio communications, for example Zigbee. tocommunicate with other networked devices.

FIG. 8A is a schematic diagram showing aspects of circuitry in an AHCUfor transmitting messages from to thermostat, according to someembodiments. Communication with the thermostat 102 uses the O/B wire,referenced from the C wire. Node 814 is connected to one of the wiringterminal 730 (shown in FIG. 7) to an O/B wire that runs to the O/Bterminal of the thermostat 102. Node 812 is connected to themicrocontroller 608 (shown in FIG. 6) The circuitry 810 provides anominal negative pull down that will appear at the microcontroller onthe backplate 542 of thermostat 102 as a logical low. A logical high isdriven by changing the pull-down to a pull-up by the thermostat 102.Node 812 has an impedance of ˜3K when pulled up. The signaling level iscompatible with an O/B voltage detection circuit on thermostat 102. Whenthe O/B switch is open in the thermostat 102, node 812 floats at about−10V. When the O/B switch is closed in the thermostat 102, note 814 ispulled to +35V. The −10V offset is used to generate the 0V low at themicrocontroller on the back plate of thermostat 102.

FIG. 8B is a schematic diagram showing aspects of circuitry within anAHCU for receiving messages from a thermostat, according to someembodiments. The thermostat sends a signal to the AHCU by turning on andoff the W1 switch at the thermostat, which is connected to node 822 isto the through wiring terminal 730 (shown in FIG. 7), and the signal ispassed through node 832 which is connected to the microcontroller 608(shown in FIG. 6). An L signal is commonly used to indicate that therehas been a fault in the HVAC system, (for example an over-currentcondition at the compressor during a start or a run). AHCU receives a24VAC signal from the furnace via the L wire terminal (e.g. see terminal646 on FIG. 6). The AHCU 460 microcontroller 608 (shown in FIG. 6)monitors this signal at high impedance, and reports it back tothermostat 102 via an encoded message via the O/B wire. According tosome embodiments, error codes can be decoded by the AHCU 460.

FIG. 8C is a schematic diagram showing aspects of circuitry within anAHCU for sending variable fan speed signal to an HVAC system, accordingto some embodiments. The nodes 842 and 844 are driven by themicrocontroller 608 on the AHCU (shown in FIG. 6) into circuitry 840 todrive the V wire signal at node 850 which is connected to the V wire ofthe HVAC system. The V wire signal is a pulse-width-modulated (PWM)signal to the HVAC system for controlling variable fan speed. The periodis a nominal 1 second, the voltage is nominal ˜10V. The signaling rangesfrom a minimum of 350 ms on for 40%, to 950 mS on for 100%.

FIG. 8D is a schematic diagram showing aspects of circuitry within anAHCU for detecting a reset signal, according to some embodiments. If thewire via node 852 is held closed for longer than a data byte then areset of the AHCU is generated using circuitry 850. According to someembodiments communication is carried out similarly to RS-232, where foreexampled there is a stop bit every 10 bit times which resets the circuitand prevents a reset form being inadvertently generated by messages ofdata containing all logical 1's.

Thus, the AHCU 460, as described, is configured to provide power and acommunication link to the thermostat 102 using substantially fewer wiresthan needed for conventionally controlling the HVAC system.Additionally, the circuitry required to generate some types of controlsignals, such as “V” wire signal, is provided on the AHCU instead of onthe thermostat 102 where space is more valuable due to the desirabilityof a small sleek visually pleasing unit. Furthermore, a “safe” (in termsof not having accidental tripping risk due to the use of power stealing)form of power is supplied to the thermostat without the use of aseparate C wire running to the thermostat. This is beneficial, forexample, in cases when a common wire is not present and certain types ofthermostat relays and/or switches make power stealing impractical. Insuch cases the use of the AHCU avoids the cost of adding a common wirebetween the HVAC system and the thermostat.

Other applications in a smart home setting for the described auxiliaryunit include: an auxiliary box for controlling an irrigation system(where there can be large numbers of individually controllableirrigation lines), and a home entertainment system (which can includemultiple components, speakers, monitors, etc. installed in variouslocations), as well as other devices that are shown in FIG. 1.

FIG. 9 shows an example of a thermostat connected to a cascadedarrangement of multiple auxiliary control units configured to controldifferent types of smart home equipment, according to some embodiments.In the example shown, thermostat 102 is connected via wires 480 to theAHCU 460, which is in turn used to control the HVAC system 103A viawires 490, as has been described herein. The RS-422 port of AHCU 460 isthen used to connect the RS-422 port of an auxiliary irrigation systemcontrol unit (AICU) 920 via wires 912. The AICU 920 is very similar tothe AHCU 460 as described herein, and can include many of the samefeatures including the “train-map” type display on the front panel ofAICU 920. The AICU is configured to control a number of irrigationcontrol units 930, 932 and 934, which in turn are used to controlirrigation control valves, such as valve 936 being controlled byirrigation control unit 930. Through a cascaded arrangement of auxiliarycontrol units such as shown, which can include additional other types ofauxiliary control units configured to control other smart homeequipment, a single thermostat 102 can be used to control a very widevariety and larger numbers of individual devices that each use differenttypes of communication protocols. Additionally, the thermostat 102 hasaccess to various information via link to other networks such a shown inFIGS. 2-3, which can advantageously be used. For example the currentweather and forecast weather information can be used in adjusting theirrigation controllers 930, 932 and 934.

Various other modifications may be made without departing from thespirit and scope of the invention. It is to be further appreciated thatthe term thermostat, as used hereinabove and hereinbelow, can includethermostats having direct control wires to an HVAC system, and canfurther include thermostats that do not connect directly with the HVACsystem, but that sense an ambient temperature at one location in anenclosure and cooperatively communicate by wired or wireless dataconnections with a separate thermostat unit located elsewhere in theenclosure, wherein the separate thermostat unit does have direct controlwires to the HVAC system. Accordingly, the invention is not limited tothe above-described embodiments, but instead is defined by the appendedclaims in light of their full scope of equivalents.

1. A thermostat adapted for direct connection either to a Heating,Ventilation, and Air Conditioning (HVAC) system or to an intermediateauxiliary HVAC control unit, the thermostat comprising: a plurality ofwiring terminals each adapted to make electrical connection with one ofa plurality of control wires running between a first location where thethermostat is installed and a second location where the HVAC system isinstalled; and processors and circuitry configured and programmed tocommunicate with the intermediate auxiliary HVAC control unit directlyat the second location via one or more of the plurality of control wiresconnected to one or more of the plurality of wiring terminals, theintermediate auxiliary HVAC control unit being directly electricallyconnected to the HVAC system via a plurality of HVAC control wires, theprocessors and circuitry further configured and programmed to:automatically determine whether the intermediate auxiliary HVAC controlunit is installed, or whether the intermediate auxiliary HVAC controlunit is not installed and the plurality of control wires are connecteddirectly to both the plurality of wiring terminals and to the HVACsystem; operate in a first mode to control the HVAC system directly andreceive electrical power directly from the HVAC system when theintermediate auxiliary HVAC control unit is not installed and theplurality of control wires are connected directly to both the pluralityof wiring terminals and to the HVAC systems; and operate in a secondmode to control the HVAC system indirectly by electronicallyre-purposing at least one of the plurality of control wires such thatthe thermostat communicates with and receives electrical power from theintermediate auxiliary HVAC control unit when the intermediate auxiliaryHVAC control unit is installed.
 2. A thermostat according to claim 1wherein the processors and circuitry are further programmed tocommunicate with the intermediate auxiliary HVAC control unitbi-directionally.
 3. A thermostat according to claim 1 wherein theprocessors and circuitry are further programmed to automatically detectwhen the plurality of control wires are connected to the intermediateauxiliary HVAC control unit.
 4. (canceled)
 5. A thermostat according toclaim 3 wherein the automatic detection is based at least in part on anassessment of which of the one or more wiring terminals have wiresconnected thereto.
 6. A thermostat according to claim 1 wherein the HVACsystem includes an air mover or furnace and the intermediate auxiliaryHVAC control unit is mounted within 5 meters of the air mover orfurnace.
 7. A thermostat according to claim 6 wherein the intermediateauxiliary HVAC control unit is mounted directly on a housing of the airmover or furnace.
 8. A thermostat according to claim 1 wherein theplurality of control wires used for connection between the wiringterminals and the intermediate auxiliary HVAC control unit is fewer innumber than the plurality of HVAC control wires.
 9. A thermostataccording to claim 8 wherein the one or more of the plurality of controlwires is at most four wires.
 10. A thermostat according to claim 9wherein the one or more of the plurality of control wires is at mostthree wires.
 11. (canceled)
 12. A thermostat according to claim 1wherein the intermediate auxiliary HVAC control unit is capable ofcontrolling a variable fan speed using a pulse-width-modulated controlsignal.
 13. A thermostat according to claim 1 wherein the intermediateauxiliary HVAC control unit includes a graphic display visible to ahuman viewing the display, the display indicating to the human which ofa plurality of HVAC control wires connecting the intermediate auxiliaryHVAC control unit to the HVAC system are currently electricallyconnected to each other.
 14. A thermostat according to claim 1 whereinthe thermostat when mounted on a wall occupies no more than 100 squarecentimeters, and the plurality of wiring terminals are configured fortool-free wire connection.
 15. A system for controlling an HVAC aHeating, Ventilation, and Air Conditioning (HVAC) system comprising: athermostat installed in a first location comprising: a plurality ofwiring terminals each adapted to make electrical connection with one ofa plurality of control wires running between the first location and asecond location where the HVAC system is installed; and processors andcircuitry configured and programmed to communicate with an intermediateauxiliary HVAC control unit via one or more of the plurality of controlwires connected to one or more of the plurality of wiring terminals, theprocessors and circuitry further configured and programmed to:automatically determine whether the intermediate auxiliary HVAC controlunit is installed, or whether the intermediate auxiliary HVAC controlunit is not installed and the plurality of control wires are connecteddirectly to both the plurality of wiring terminals and to the HVACsystem; operate in a first mode to control the HVAC system directly andreceive electrical power directly from the HVAC system when theintermediate auxiliary HVAC control unit is not installed and theplurality of control wires are connected directly to both the pluralityof wiring terminals and to the HVAC system; and operate in a second modeto control the HVAC system indirectly by electronically re-purposing atleast one of the plurality of control wires such that the thermostatcommunicates with and receives electrical power from the intermediateauxiliary HVAC control unit when the intermediate auxiliary HVAC controlunit is installed; and the intermediate auxiliary HVAC control unitinstalled in the second location where the HVAC system is installed, theintermediate auxiliary HVAC control unit being directly electricallyconnected to the HVAC system via a plurality of HVAC control wires, theintermediate auxiliary HVAC control unit comprising: a first set ofauxiliary unit wiring terminals each adapted to make electricalconnection with one of the plurality of control wires running betweenthe first location and the second location; a second set of auxiliaryunit wiring terminals each adapted to make electrical connection withone of the plurality of HVAC control wires running between theintermediate auxiliary HVAC control unit and the HVAC system; aplurality of relays used to open and close connections betweenconductors leading to the second set of auxiliary unit wiring terminals;and a graphic display visible to a human viewing the display, thedisplay indicating to the human a status of one or more of the pluralityof relays so as to show to the human which of the second set ofauxiliary unit wiring terminals are currently electrically connected toeach other.
 16. A system according to claim 15 wherein the graphicdisplay includes a plurality of visible LEDs which indicate status ofone or more of the relays.
 17. A system according to claim 15 whereinthe intermediate auxiliary HVAC control unit further comprises one ormore wiring terminals adapted to make electrical connection to one ormore wires leading to one or more remote temperature sensors.
 18. Asystem according to claim 17 wherein the one or more remote temperaturesensors measures one or more temperatures selected from a groupconsisting of: outdoor air temperature, indoor air temperature andreturn air temperature.
 19. A system according to claim 15 wherein thegraphic display includes lines representing conductors silkscreened ontoan external housing of the intermediate auxiliary HVAC control unit. 20.A system according to claim 15 wherein the intermediate auxiliary HVACcontrol unit further comprises a wireless communication moduleconfigured to wirelessly communicate with at least one other devicelocated with an enclosure conditioned by the HVAC system.
 21. A systemaccording to claim 15 wherein the first set of auxiliary unit wiringterminals are further adapted to make connection to a second thermostat.22. A system according to claim 21 wherein the second thermostat can belocated in the second location and be temporarily connected for use ininstallation of and/or diagnostics relating to the intermediateauxiliary HVAC control unit.
 23. A system according to claim 15 whereinthe intermediate auxiliary HVAC control unit further comprises circuitryfor generating a pulse-width-modulated control signal for controllingvariable speed on an HVAC component.
 24. A system according to claim 15wherein the intermediate auxiliary HVAC control unit further comprisescircuitry for supplying electrical power to the thermostat through thefirst set of wiring terminals, said electrical power not being switchedin order to control HVAC functions.
 25. A system according to claim 24wherein the electrical power is DC electrical power.
 26. (canceled)